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Irrigated Corn as a Source of Barley Yellow Dwarf Virus and Vector in Eastern Washington. J. K. Brown, Department of Plant Pathology, Washington State University, Pullman 99164-6430, Present address of senior author: Department of Plant Pathology, University of Arizona, Tucson 85721; S. D. Wyatt(2), and D. Hazelwood(3). (2)(3)Department of Plant Pathology, Washington State University, Pullman 99164-6430. Phytopathology 74:46-49. Accepted for publication 10 May 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-46.

Barley yellow dwarf virus (BYDV) causes economic loss in winter grain crops in eastern Washington when seedlings become infected shortly after emergence. Irrigated corn was identified as a reservoir of the virus and its aphid vectors during the interim between summer harvest and fall planting of winter grains. Although foliar symptoms were not associated with BYDV-infected corn plants, 58 and 65% of the corn fields surveyed in the Columbia Basin harbored the virus in 1981 and 1982, respectively. Viruliferous Macrosiphum avenae (Aphididae) were present in late June and July, 1980, but the largest aphid populations, which consisted of Rhopalosiphum padi, were present in August and September. Sixty-one percent of the R. padi collected from corn in 1980 were viruliferous. In 1981, viruliferous M. avenae was noted in corn fields in June, while R. padi infested 36, 11, and 90% of the corn fields surveyed in July, August, and September, respectively. Virus was recovered from all but one of 75 corn cultivars, hybrids, or lines when experimentally inoculated by R. padi in greenhouse studies. Over 50% of the corn tested exhibited foliar symptoms under greenhouse conditions, usually a red discoloration of the leaves. Aphid transmission and ELISA test results suggest BYDV isolates from corn are similar to previously identified vector-nonspecific isolates from wheat fields in Washington.

Additional keywords: maize virus, symptomless infection, yellow dwarf.